The present invention relates generally to post pullers and, more particularly, to an improved attachment for use with hydraulic power sources for pulling posts from the ground.
The removal of highway guardrails and fence posts, especially those mounted in concrete, is a very difficult task. This task is frequently accomplished in a rather haphazard and unsafe manner. Generally, extracting a post may be accomplished by wrapping a chain around the post, then pulling up on the chain until it is tight and will xe2x80x9cbindxe2x80x9d on the post. This requires a minimum of two personsxe2x80x94one to wrap the chain and keep a xe2x80x9cbindingxe2x80x9d force tension on the chain, and one to operate the machine to lift or pull the post from the ground. This is a dangerous operation because the person wrapping the chain onto the post must manually keep tension of the chain while the equipment operator pulls the chain tight, and often the operator cannot fully see the other person while operating the machine. Highway guardrails are pulled in a similar mannerxe2x80x94either by wrapping the guardrail with a chain or attaching a cable to the guardrail with a plate clamp or similar device. Additionally, the second person or helper must also unchain or unclamp the post or guardrail in order to move on the next one.
In addition, apparatus for pulling posts out of the ground are known in the art. Some such apparatus are so designed that they must be transported by hand to the site where they are to be used. Other apparatus, although designed to be vehicle mounted, are not provided with sufficient positive extracting force to be used for posts of larger sizes or that are set relatively deeply in the ground. Still others which are designed to be motor vehicle mounted have a minimal radius of operation or, at best, are confined to operation within an extremely limited radius from the vehicle. Still other post puller designs are incapable of effective use for removing posts of various diameters or cross-sectional shapes.
The forces required to pull a post from the ground are often very large and indeterminate, due to unknowns such as soil compaction, soil type, suction, and other unknown variables. Therefore, many prior art post pulling machines are incapable of pulling a post from the ground, even if there were a method of clamping or gripping the post. The actual pulling or lifting function often requires the use of a large machine, due to the high breakout lifting forces required. These larger machines are required because they must supply all of the lifting or pulling force. These larger machines can also be a hazard when operating in the confined spaces of a heavily traveled highway.
Accordingly, it is an object of the present invention to provide post puller adapted to be mounted on a prime mover or vehicle with a hydraulic power source that addresses the disadvantages of the above-described prior art.
It is a further object of the present invention to provide a post puller attachment that grips the post from the side or front and that is adapted to clamp the object to be removed from the ground relatively low to the ground.
It is still a further object of the present invention to provide a post puller attachment wherein the initial lifting or breakout force is supplied by the attachment which reacts against the ground and, as a result, is adaptable for use with relatively smaller and more maneuverable handling machinery such as skid steer loaders or small tractors.
It is yet a further object of the present invention to provide a post puller attachment which is characterized by rugged construction and ease of use.
Still other objects of the present invention will become apparent to those skilled in this art from the following description and drawing wherein there is described and shown a preferred embodiment of the invention. As will be realized, the invention is capable of other different embodiments, and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.
To achieve the foregoing and other objects, and in accordance with one aspect of the present invention, an improved post puller is provided. The improved hydraulically operated post pulling apparatus is adapted to be mounted on a vehicle such as a skid steer mover. The post puller apparatus includes a support frame adapted to be mounted on the vehicle. The support frame includes a number of base member brackets that attach a base member or base plate to the support frame. The base member includes a post receiving recess that is adapted to receive a post from the side rather than the top.
The post pulling apparatus also includes a top support plate that also includes a post receiving indent, which is also adapted to receive a post from the side rather than the top. A rotating jaw member that includes a plurality of post-engaging teeth is pivotally mounted next to the post receiving indent on the top support plate. Opposite the rotating jaw member and also next to the post receiving indent, a fixed jaw member is attached to the top support plate that includes a number of post-engaging faces. A clamping cylinder is mounted to the top support plate and includes a piston that is pivotally attached to the rotating jaw member. The piston, when extended, operates to pivot the rotating jaw member downwardly into engagement with the post to be engaged and removed from the ground. First and second pairs of bar links are each pivotally mounted at one end to the support frame and pivotally mounted at an opposite end to a forward panel that is preferably attached to the rear of the support plate. A pair of pulling hydraulic cylinders are mounted on the base member, each having a piston attached to the top support plate. When the pistons of the pulling hydraulic cylinders are extended, the bar links pivot allowing the top support plate to lift and raise the pole from the ground.